Radio-frequency circuit and communication device

Abstract

The present disclosure facilitates impedance matching between a power amplifier and filters. A radio-frequency circuit includes a power amplifier, a plurality of transmit filters, a switch, a plurality of first matching networks, and a second matching network. The switch switches the plurality of transmit filters to be coupled to the power amplifier. The plurality of first matching networks are coupled between the plurality of transmit filters and the switch. The second matching network is coupled between the power amplifier and the switch. The second matching network includes a transmission line transformer.

The invention claimed is: 
     
       1. A radio-frequency circuit comprising:
 a power amplifier; 
 a plurality of transmit filters; 
 a switch configured to selectively couple the plurality of transmit filters to the power amplifier; 
 a plurality of first matching networks coupled between the plurality of transmit filters and the switch; and 
 a second matching network coupled between the power amplifier and the switch, the second matching network comprising a transmission line transformer. 
 
     
     
       2. The radio-frequency circuit according to  claim 1 , wherein:
 the transmission line transformer comprises:
 a first winding coupled between the power amplifier and the switch, and 
 a second winding coupled between the power amplifier and ground, 
 
 the second winding is adjacent to the first winding with respect to a first direction, and 
 a direction of current flow in the second winding is opposite to a direction of current flow in the first winding with respect to a second direction, the second direction being perpendicular to the first direction. 
 
     
     
       3. The radio-frequency circuit according to  claim 2 , comprising two first windings, wherein:
 the two first windings are coupled in series with each other between the power amplifier and the switch, 
 the direction of current flow of each of the two first windings are identical to each other, and 
 the second winding is between the two first windings with respect to the first direction. 
 
     
     
       4. The radio-frequency circuit according to  claim 3 , wherein each of the plurality of first matching networks is configured to reduce a harmonic component of a radio-frequency signal from the power amplifier. 
     
     
       5. The radio-frequency circuit according to  claim 3 , further comprising:
 a mounting board, 
 wherein the transmission line transformer is a conductor that is mounted at the mounting board. 
 
     
     
       6. The radio-frequency circuit according to  claim 3 , further comprising:
 a mounting board, 
 wherein the transmission line transformer is a single chip that is mounted at the mounting board. 
 
     
     
       7. The radio-frequency circuit according to  claim 2 , wherein each of the plurality of first matching networks is configured to reduce a harmonic component of a radio-frequency signal from the power amplifier. 
     
     
       8. The radio-frequency circuit according to  claim 2 , further comprising:
 a mounting board, 
 wherein the transmission line transformer is a conductor that is mounted at the mounting board. 
 
     
     
       9. The radio-frequency circuit according to  claim 2 , further comprising:
 a mounting board, 
 wherein the transmission line transformer is a single chip that is mounted at the mounting board. 
 
     
     
       10. The radio-frequency circuit according to  claim 1 , wherein each of the plurality of first matching networks is configured to reduce a harmonic component of a radio-frequency signal from the power amplifier. 
     
     
       11. The radio-frequency circuit according to  claim 10 , further comprising:
 a mounting board, 
 wherein the transmission line transformer is a conductor that is mounted at the mounting board. 
 
     
     
       12. The radio-frequency circuit according to  claim 10 , further comprising:
 a mounting board, 
 wherein the transmission line transformer is a single chip that is mounted at the mounting board. 
 
     
     
       13. The radio-frequency circuit according to  claim 1 , further comprising:
 a mounting board, 
 wherein the transmission line transformer is a conductor that is mounted at the mounting board. 
 
     
     
       14. The radio-frequency circuit according to  claim 13 , wherein the transmission line transformer is disposed between the power amplifier and the switch at the mounting board. 
     
     
       15. The radio-frequency circuit according to  claim 1 , further comprising:
 a mounting board, 
 wherein the transmission line transformer is a single chip that is mounted at the mounting board. 
 
     
     
       16. The radio-frequency circuit according to  claim 15 , wherein:
 a circuit component of the power amplifier or of the switch is mounted on the mounting board, and 
 the transmission line transformer is stacked on the circuit component. 
 
     
     
       17. The radio-frequency circuit according to  claim 15 , wherein:
 the power amplifier and the switch are included in a single chip, and 
 the transmission line transformer is stacked on the chip. 
 
     
     
       18. The radio-frequency circuit according to  claim 15 , wherein the transmission line transformer is between the power amplifier and the switch at the mounting board. 
     
     
       19. The radio-frequency circuit according to  claim 1 , wherein the transmission line transformer is a conductor that is mounted on the power amplifier or the switch. 
     
     
       20. A communication device comprising:
 the radio-frequency circuit according to  claim 1 ; and 
 a signal processing circuit configured to process a radio-frequency signal that is transferred to the radio-frequency circuit.